Offered by the Deutsche Bahn railway company, Germany's Call a Bike system allows riders to use their cellphones to unlock bikes that are left near train stations.

By Anne VanderMey, reporter @FortuneMagazine - Last updated July 19 2012: 8:49 AM ET
Join the Conversation
Google's zero-carbon quest

The search giant has an ambitious plan to achieve its goal: becoming the world's most energy-efficient company.